ABSTRACT: , Trans Women Connected: a mobile app delivered sexual health promotion program During the past two decades, the HIV epidemic has severely impacted transgender women in the U.S. According to the CDC persons have the highest HIV incidence of any risk group (56% of Black transgender women are living with HIV), and discrepancies between self-reported prevalence and HIV testing data indicate that many HIV-infected transgender women are not aware of their HIV status. Other public health conditions among transgender women include discrimination-based physical and verbal abuse, poor mental health, alcohol and drug use, and unmet health care needs resulting from limited healthcare access and negative healthcare encounters. These co-occurring problems additively increase sexual risk for transgender women. Despite these health disparities and health-care access barriers, the U.S. National HIV/AIDS Strategy notes that HIV prevention efforts specifically targeting transgender populations have been minimal, leaving a dearth of evidence-based programs that address the unique needs of transgender women, leaving practitioners to implement programs designed for men who have sex with men (MSM) or cisgender women, even though transgender women's experiences of gender abuse, gender transition, transactional sex and violence distinguish them from most MSM and cisgender women. This project will address these gaps by completing the development of Trans Women Connected: A Sexual Health Promotion Mobile App designed to engage transgender women through a strengths-based approach to HIV/sexual health that uses the power of social networks to identify and encourage protective factors that support the health and well-being of transgender women. Based on the needs of transgender women identified during Phase I research the app will focus heavily on sexual health/harm reduction, identity affirmation, structural issues impacting health, and connectedness. At the end of Phase II the mobile delivered intervention will expand the HIV prevention opportunities for transgender women by (1) providing organizations a cost-effective and easily implementable intervention option that is specifically designed for transgender women; (2) not requiring participants to attend multiple face-to-face sessions in a physical location and instead support iterative intervention implementation at any time or place; (3) permit transgender women to anonymously view the program on their phone in private settings; and (4) offer an effective means for transgender women to connect with each other and providers via mobile technology. The Phase I project demonstrated feasibility in creating an app that changed knowledge and intentions of users with just three activities, while being appealing to the target audience. Phase II will complete the development of the app with 40+ activities, a forum/messaging system for social support/connection, all developed with input from panels of experts and community members. A randomized controlled will assess the effectiveness of the app using a number of measures including STI prevention, improvement in health care seeking, perceived social support.